1. Field of the Invention
The present invention relates to a transformer of power-amplifier module for an audio device and, more particularly, to a transformer of power-amplifier module whose inputs and outputs are controlled by magnetic coupling to achieve broadband transmission and is suitable for apply in amplifier of audio equipments or other similar ones.
2. Description of Prior Art
It is well known that using electron tubes is the best way to have amplifier of audio equipments a rich voice. But the amplifier of electron tubes is by valves such that the load speaker wording in 4xcx9c8 will be in the high voltage status. Consequently it is difficult to insulate, hard to keep in good repair at high energy consume and low power with around 3000 to 5000 hrs life-span, and expensive in manufacturing cost that it is not easy to.
Amplifiers adjusted with variable transistors are widely used now. It is found in any audio device that these amplifiers, particular power-amplifiers, are connected sequentially in a resistance-capacitance coupled manner and that a variable resistor is used to adjust loudness of an audio. These result in cheaper manufacturing cost but may lose tone quality. However to raise the tone quality it is necessary to use electronic tubes and there is no other choice up to now. Actually for some expensive audios it is indispensable to raise their acoustics. Besides, the output of an audio through loudspeakers with different sensitivities should collocate with suitable thrust or the sound will not harmonize.
The components used in the audio circuit in current is of fixed type which is a circuit composed of one or more transistors connected in push-pull form. The selection and distribution of components were well planned while designing the board and after the electronic circuit has been set up the function and range of signal administration has been limited, such that there is no maneuver variation in amplification power and of course its acoustics can not adjust suitably with different loudspeakers. In addition, this design of whole board will occupy more space in casing fabrication because of its outward appearance has been fixed.
Therefore, the motive of the present invention is to improve those shortcomings of the prior arts and to provide a transformer of power-amplifier module for an audio device whose volume can be controlled by magnetic coupling and can be connected in series for loudspeakers with different sensitivities.
The object of the present invention is to provide a transformer of power-amplifier module, which organizes the amplification circuits to control the volume.
Another object of the present invention is to provide a transformer of power-amplifier module that several transformer of power-amplifier modules of different amplification ratios can used in series connection to collocate with loudspeakers with different sensitivities.
To accomplish the objects above, the transformer of power-amplifier module in the present invention is mainly comprised of a casing, in which an amplifying circuit regulated by a magnetic coupling is established; there is a first plug, corresponding to the input of the amplifying circuit interior, positioned at one end of the casing; there is a second plug corresponding to the output of the amplifying circuit interior, positioned at another end of the casing; the volume is controlled by modifying the magnetic coupling, and several modules can be used in series connection.